The Collaborative International Dictionary of English v.0.48:

Barracuda \Bar`ra*cu"da\, Barracouta \Bar`ra*cou"ta\,, n.
   [Native name.] (Zool.)
   Any of several voracious pikelike marine fishes allied to the
   gray mullets, constituting the genus Sphyr[ae]na and family
   Sphyr[ae]nid[ae]. The great barracuda (Sphyr[ae]na
   barracuda) of the West Indies, Florida, etc., is often six
   feet or more long, and as dangerous as a shark. In Cuba its
   flesh is reputed to be poisonous. Sphyr[ae]na Argentea of
   the Pacific coast and Sphyr[ae]na sphyr[ae]na of Europe are
   smaller species, and are used as food.
   [Webster 1913 Suppl.]

   Note: That of Europe and our Atlantic coast is Sphyr[ae]na
         spet (or Sphyr[ae]na vulgaris); a southern species
         is Sphyr[ae]na picuda; the Californian is
         Sphyr[ae]na argentea.
         [1913 Webster]

   2. (Zool.) A large edible fresh-water fish of Australia and
      New Zealand (Thyrsites atun).
      [1913 Webster]

WordNet (r) 3.0 (2006):

barracuda
    n 1: any voracious marine fish of the genus Sphyraena having an
         elongated cylindrical body and large mouth with projecting
         lower jaw and long strong teeth